284 ON THE COMBINATIONS OF 
this conclusion arrived at by Dr. Thomson, I 
commenced a repetition of his experiments. 
Having carefully prepared the different 
strengths of acid required, as far as that sp. gr. 
1.4737=1 atom acid to 5 water; by diluting 
oil of vitriol sp. gr. 1.8436, (specially prepared 
for me by a friend, and the impurity of which 
I found to amount only to about the ;5th of 
one per cent.) with the requisite quantities of 
water, I found their specificheats by puttingthem 
into a glass bulb,* capable of holding about 2400 
grains of water of the temperature of 60°, sus- 
pended in the centre of a room, and noting the 
times required for cooling from 130° to 100°, 
the temperature of the ambient air being ex- 
actly 56°:—the temperature of the liquid in the 
bulb was indicated by a thermometer, passed 
through the cork in the neck of the bulb, the 
stem of which had been marked by a file where 
the mercury rose to at 100° and 130°. 
I found the bulb when filled with water, to 
require 2500 seconds for cooling ; and when 
empty 179 seconds. 
*In every case, the bulb had as much of the liquid put into 
it as reached up to a mark at the bottom of the neck, when the 
temperature of the liquid was 130°. 
